Along with gem stones (e.g., diamond, ruby, emerald, topaz, opal, jade), and precious metals (e.g., gold, silver, platinum), pearls are among the most prized possessions (or luxury items) for human beings for millenniums. Beside their natural beauty, the brilliant color and luster, they are often associated with social status and level of well-being. As a result, and not surprisingly, the trend of cosmetics makeup is to emulate or recreate these “natural” and “aesthetic” appearances of pearl, gem and precious metals with less expensive materials such as interference pigments (e.g., metal oxide coated mica). The most common types of pearlescent pigments are micronized titanium dioxide, metal oxide coated mica, metal oxide coated alumina, metal oxide coated silica, basic lead carbonate, bismuth oxychloride, and natural fish silver.
Metal oxide coated mica pigments are characterized by excellent optical, chemical, mechanical, toxicological, and environmental properties. Natural or synthetic mica, and alternative supports, such as aluminum flakes, or SiO2 platelets, can be used alone, or as a support for titanium dioxide, iron oxide (Fe2O3 or Fe3O4), iron ferrocyanide (Iron Blue or Prussian Blue), tin oxide, and chromium oxide. The color space defined by these coated mica-based pigments is based on the type of coating (e.g. metal oxide, colorant, etc.) used, the layer thickness, and the number of coated layers.
Among pigments, orange is a difficult color to produce. Orange pigments have typically used cadmium, which is not environmentally friendly. Orange pearlescent pigments are especially rare. There are some pigments sold by Merck under the trade name “IRIO-DIN 500,” however they are not pearl pigments having an orange color of high chroma. Merck found that mica or like substrates coated with ferric oxide alone fail to show any coincidence between the maximum Hunter color tone values of a and b and thus no pearl pigment having an orange color with a high chroma can be obtained, U.S. Pat. No. 6,190,445.
Another example of orange colored pearlescent pigments currently offered in the market is Paliocrom® Orange L 2800 (an iron-oxide coated aluminum based pigment) by BASF. The existing pearlescent products in the market typically have a low chroma, and a hue angle that is not close to 45 degrees.
Consequently, a need exists for orange pearlescent pigments with a high chroma.